This invention relates to stethoscopes in general and in particular to stethoscopes including electronic amplification circuitry. Still more particularly, this invention relates to improved electronic stethoscopes having enhanced noise rejection characteristics and automatic power conservation circuitry and which are designed to resemble simple acoustic stethoscopes in size and convenience.
Both electronic and acoustic stethoscopes and combinations of these two are well known in the art. One example of an electronic stethoscope is described in U.S. Pat. No. 3,247,324. That stethoscope includes a pickup head which is acoustically coupled, by means of a flexible conduit, to a microphone. The signals picked up by that microphone are then amplified and provided to a speaker which is acoustically coupled to a conventional binaural headpiece by means of flexible conduits. The stethoscope disclosed in U.S. Pat. No. 3,247,324 also permits direct acoustical connection between the pickup head and the binaural headpiece.
Electronic stethoscopes known in the prior art have not been generally accepted by medical practitioners due to several problems which exist in those designs. Typically, these known devices have been bulky and difficult to utilize, carry or store. Further, known electronic stethoscopes have suffered from reliability problems due to battery problems and interference due to background high frequency interference from fluorescent light fixtures or other sources. Clearly, there has existed a need for an electronic stethoscope which is physically similar to acoustic stethoscopes in size and convenience and which is not subject to the vagaries of known circuitry.